Certainly when I used mounts for units in P&N, it was for those reasons:
1) Prevents the mount from being used on a ship that is too large. (EG, more efficient shields on really small craft in P&N, smaller engine mounts in mQNP systems)
2) Avoids the need to worry about whether max and min are inclusive
If they were set to exactly the tonnage of the ship, it would have to be tested to make sure it works.
3) It allows you to add new ship sizes without worrying about the pre-existing mounts accidentally being available.
[ November 07, 2003, 18:41: Message edited by: Suicide Junkie ]